Control circuits are well known for driving d-c motors. H-bridge circuits are commonly employed which employ two high side MOSFETs and two low side MOSFETs in which each high side device is in series with a respective low side device. The nodes between the pairs of high side and low side devices, hereinafter M1 and M2 respectively, are connected to the motor terminals; the drains of each of the high side devices are connected to a d-c source such as a battery, hereinafter Vcc, and the sources of each of the low side devices are connected to ground (hereinafter GND).
A control circuit is then provided to turn the high side and low side devices on and off to drive current through the motor windings in directions to cause rotation of the motor rotor in a clockwise or counterclockwise direction.
The MOSFETs used for such circuits are commonly individually mounted as discrete devices; and the control circuits for controlling their conduction have also been formed of discrete circuits or combinations of several integrated circuits and discretes. Further, complicated programmed circuits have also been necessary to the circuit control. All of this increases complexity and cost and reduces reliability of the control.
It would be desirable to reduce the component count of such circuits; and to simplify their operation and to avoid the need for programmed control functions.